Kotaku’s Jason Schreier reported that developers have been working on this too, to make games compatible with Sony’s plans. That said, there’s no indication as to when this will actually be a thing.
Schreier’s sources also shared that because your username was a key part of your PSN ID, the challenge is to make it so that you can change your username at will, with something else taking the key role of identifier for your account. And it’s likely something that every game with an online component needs to sort out first before Sony can implement these changes, lest things you purchased are suddenly untied from your account.
Sony’s PlayStation has been on a roll recently, what with its sudden reversal on its stance on cross play, even if it’s only for one game. Hopefully the implementation on the username change is also a friendly one, allowing for free changes like Steam while still letting others identify you by showing other usernames you’ve used in the past. (Source: Kotaku)